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10544ee8 MD |
1 | #ifndef _LTTNG_UST_FUTEX_H |
2 | #define _LTTNG_UST_FUTEX_H | |
3 | ||
4 | /* | |
5 | * liblttng-ust/futex.h | |
6 | * | |
7 | * Userspace RCU - sys_futex/compat_futex header. | |
8 | * | |
9 | * Copyright 2011-2012 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
10 | * | |
11 | * This library is free software; you can redistribute it and/or | |
12 | * modify it under the terms of the GNU Lesser General Public | |
13 | * License as published by the Free Software Foundation; either | |
14 | * version 2.1 of the License, or (at your option) any later version. | |
15 | * | |
16 | * This library is distributed in the hope that it will be useful, | |
17 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
18 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
19 | * Lesser General Public License for more details. | |
20 | * | |
21 | * You should have received a copy of the GNU Lesser General Public | |
22 | * License along with this library; if not, write to the Free Software | |
23 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | |
24 | */ | |
25 | ||
26 | #include <errno.h> | |
27 | #include <stdint.h> | |
28 | #include <time.h> | |
29 | #include <sys/syscall.h> | |
30 | ||
9f47aac8 MJ |
31 | #include "helper.h" |
32 | ||
10544ee8 MD |
33 | #ifdef __cplusplus |
34 | extern "C" { | |
35 | #endif | |
36 | ||
37 | #define FUTEX_WAIT 0 | |
38 | #define FUTEX_WAKE 1 | |
39 | ||
40 | /* | |
41 | * sys_futex compatibility header. | |
42 | * Use *only* *either of* futex_noasync OR futex_async on a given address. | |
43 | * | |
44 | * futex_noasync cannot be executed in signal handlers, but ensures that | |
45 | * it will be put in a wait queue even in compatibility mode. | |
46 | * | |
47 | * futex_async is signal-handler safe for the wakeup. It uses polling | |
48 | * on the wait-side in compatibility mode. | |
49 | * | |
50 | * BEWARE: sys_futex() FUTEX_WAIT may return early if interrupted | |
51 | * (returns EINTR). | |
52 | */ | |
53 | ||
9f47aac8 | 54 | LTTNG_HIDDEN |
10544ee8 MD |
55 | extern int lttng_ust_compat_futex_noasync(int32_t *uaddr, int op, int32_t val, |
56 | const struct timespec *timeout, int32_t *uaddr2, int32_t val3); | |
9f47aac8 | 57 | LTTNG_HIDDEN |
10544ee8 MD |
58 | extern int lttng_ust_compat_futex_async(int32_t *uaddr, int op, int32_t val, |
59 | const struct timespec *timeout, int32_t *uaddr2, int32_t val3); | |
60 | ||
61 | #if (defined(__linux__) && defined(__NR_futex)) | |
62 | ||
63 | #include <unistd.h> | |
64 | #include <errno.h> | |
65 | #include <urcu/compiler.h> | |
66 | #include <urcu/arch.h> | |
67 | ||
68 | static inline int lttng_ust_futex(int32_t *uaddr, int op, int32_t val, | |
69 | const struct timespec *timeout, int32_t *uaddr2, int32_t val3) | |
70 | { | |
71 | return syscall(__NR_futex, uaddr, op, val, timeout, | |
72 | uaddr2, val3); | |
73 | } | |
74 | ||
75 | static inline int lttng_ust_futex_noasync(int32_t *uaddr, int op, int32_t val, | |
76 | const struct timespec *timeout, int32_t *uaddr2, int32_t val3) | |
77 | { | |
78 | int ret; | |
79 | ||
80 | ret = lttng_ust_futex(uaddr, op, val, timeout, uaddr2, val3); | |
81 | if (caa_unlikely(ret < 0 && errno == ENOSYS)) { | |
82 | /* | |
83 | * The fallback on ENOSYS is the async-safe version of | |
84 | * the compat futex implementation, because the | |
85 | * async-safe compat implementation allows being used | |
86 | * concurrently with calls to futex(). Indeed, sys_futex | |
87 | * FUTEX_WAIT, on some architectures (mips and parisc), | |
88 | * within a given process, spuriously return ENOSYS due | |
89 | * to signal restart bugs on some kernel versions. | |
90 | */ | |
91 | return lttng_ust_compat_futex_async(uaddr, op, val, timeout, | |
92 | uaddr2, val3); | |
93 | } | |
94 | return ret; | |
95 | ||
96 | } | |
97 | ||
98 | static inline int lttng_ust_futex_async(int32_t *uaddr, int op, int32_t val, | |
99 | const struct timespec *timeout, int32_t *uaddr2, int32_t val3) | |
100 | { | |
101 | int ret; | |
102 | ||
103 | ret = lttng_ust_futex(uaddr, op, val, timeout, uaddr2, val3); | |
104 | if (caa_unlikely(ret < 0 && errno == ENOSYS)) { | |
105 | return lttng_ust_compat_futex_async(uaddr, op, val, timeout, | |
106 | uaddr2, val3); | |
107 | } | |
108 | return ret; | |
109 | } | |
110 | ||
111 | #elif defined(__FreeBSD__) | |
112 | ||
113 | #include <sys/types.h> | |
114 | #include <sys/umtx.h> | |
115 | ||
116 | static inline int lttng_ust_futex_async(int32_t *uaddr, int op, int32_t val, | |
117 | const struct timespec *timeout, int32_t *uaddr2, int32_t val3) | |
118 | { | |
119 | int umtx_op; | |
120 | void *umtx_uaddr = NULL, *umtx_uaddr2 = NULL; | |
121 | struct _umtx_time umtx_timeout = { | |
122 | ._flags = UMTX_ABSTIME, | |
123 | ._clockid = CLOCK_MONOTONIC, | |
124 | }; | |
125 | ||
126 | switch (op) { | |
127 | case FUTEX_WAIT: | |
128 | /* On FreeBSD, a "u_int" is a 32-bit integer. */ | |
129 | umtx_op = UMTX_OP_WAIT_UINT; | |
130 | if (timeout != NULL) { | |
131 | umtx_timeout._timeout = *timeout; | |
132 | umtx_uaddr = (void *) sizeof(umtx_timeout); | |
133 | umtx_uaddr2 = (void *) &umtx_timeout; | |
134 | } | |
135 | break; | |
136 | case FUTEX_WAKE: | |
137 | umtx_op = UMTX_OP_WAKE; | |
138 | break; | |
139 | default: | |
140 | errno = EINVAL; | |
141 | return -1; | |
142 | } | |
143 | ||
144 | return _umtx_op(uaddr, umtx_op, (uint32_t) val, umtx_uaddr, | |
145 | umtx_uaddr2); | |
146 | } | |
147 | ||
148 | static inline int lttng_ust_futex_noasync(int32_t *uaddr, int op, int32_t val, | |
149 | const struct timespec *timeout, int32_t *uaddr2, int32_t val3) | |
150 | { | |
a3bdb11c | 151 | return lttng_ust_futex_async(uaddr, op, val, timeout, uaddr2, val3); |
10544ee8 MD |
152 | } |
153 | ||
154 | #elif defined(__CYGWIN__) | |
155 | ||
156 | /* | |
157 | * The futex_noasync compat code uses a weak symbol to share state across | |
158 | * different shared object which is not possible on Windows with the | |
159 | * Portable Executable format. Use the async compat code for both cases. | |
160 | */ | |
161 | static inline int lttng_ust_futex_noasync(int32_t *uaddr, int op, int32_t val, | |
162 | const struct timespec *timeout, int32_t *uaddr2, int32_t val3) | |
163 | { | |
164 | return lttng_ust_compat_futex_async(uaddr, op, val, timeout, uaddr2, val3); | |
165 | } | |
166 | ||
167 | static inline int lttng_ust_futex_async(int32_t *uaddr, int op, int32_t val, | |
168 | const struct timespec *timeout, int32_t *uaddr2, int32_t val3) | |
169 | { | |
170 | return lttng_ust_compat_futex_async(uaddr, op, val, timeout, uaddr2, val3); | |
171 | } | |
172 | ||
173 | #else | |
174 | ||
175 | static inline int lttng_ust_futex_noasync(int32_t *uaddr, int op, int32_t val, | |
176 | const struct timespec *timeout, int32_t *uaddr2, int32_t val3) | |
177 | { | |
178 | return lttng_ust_compat_futex_noasync(uaddr, op, val, timeout, uaddr2, val3); | |
179 | } | |
180 | ||
181 | static inline int lttng_ust_futex_async(int32_t *uaddr, int op, int32_t val, | |
182 | const struct timespec *timeout, int32_t *uaddr2, int32_t val3) | |
183 | { | |
184 | return lttng_ust_compat_futex_async(uaddr, op, val, timeout, uaddr2, val3); | |
185 | } | |
186 | ||
187 | #endif | |
188 | ||
189 | #ifdef __cplusplus | |
190 | } | |
191 | #endif | |
192 | ||
193 | #endif /* _LTTNG_UST_FUTEX_H */ |